High efficiency wear-compensating gear pump



0. ECKERLE April 25, 1967 HIGH EFFICIENCY WEAR-COMPENSATING GEAR PUMP 2 Sheets-Sheet 1 Filed Aug. 23-, 1966 INVE NTOR OTTO ECKERLE ATTORNEY.

April 25, 1967 o. ECKERLE 3,315,608

HIGH EFFICIENCY WEAR-COMPENSATING GEAR PUMP Filed Aug. 23, 1966 2 Sheets-Sheet 2 IN VE NTOR OTTO ECKERLE ATTORNEY.

' a balancing area.

United States Patent Ofi 3,3 15,6 08 Patented Apr. 25, 1967 ice E 13 Claims. (Cl. 103-126) The invention relates to an internally geared pump having a driven pinion toothed on the outside and a rotating floatingly arranged ring gear which is toothed on the inside, this Wheel being pressed, with the aid of a control piston, against a filling piece which is movably mounted between the piston and the ring gear.

The invention concerns the problem of compensating, as accurately as possible, the forces effective upon the movable parts, such as the filling piece, the ring gear, and the control piston, or to overcompensate these forces to a minor extent, so that all these parts remain in sealing engagement with one another, the mechanical load being only very small, and at the same time the filling piece is brought into sealing engagement with the pinion. Furthermore, the invention is based on the problem to compensate the forces effective upon the filling piece in such a manner that the remaining residual resultant of the forces eflective upon the filling piece extends through the geometrical axis of the pin of the filling piece, so that pitching moments of the filling piece are avoided.

In order to solve this problem, it is proposed to guide the pin of the filling piece in slots located in axial plates, which later are usually provided in such pumps. Such slots extend exactly at right angles to the direction of the resultant force effective upon the filling piece. Furthermore, the sealing cross-sectional areas of the filling piece are positioned, by means of appropriate grooves, slots, bores, or channels in the filling piece, in the area of the filling piece, or in the control piston, in such a manner that the forces resulting therefrom, together with the other forces efl ective transversely or radially to the filling piece, yield a total load extending through the axis of the pin of the filling piece.

The expression cross-sectional sealing area means that cross-sectional area of the filling piece positioned between two respectively opposed teeth of the pinion and the ring gear. The force resulting from the sealing cross section is the central normal upon the cross-sectional area.

The invention relates furthermore to the control piston which is mounted by means of an intermediate guide pin received in a slot-of the housing; this control piston has Since the control piston is under a heavy load on account of the balancing field effective thereupon, and is additionally subjected to strong bending forces on account of its central suspension, it has turned out to be advantageous to split the compensating pressure field effective upon its rear into two portions, and to provide two pistons under spring tension which are effective upon the two halves of the control piston. Thereby, the bending moment effective upon the central, relatively weak part of the control piston is absorbed by each half and thus becomes ineffective.

Of course, it is also possible to provide several compensating pistons, or one elongated compensating piston extending almost across the entire rear of the control piston. I

It is, furthermore, necessary not to employ the axial plates serving for mounting the filling piece at the same time for a lateral sealing of the pressure chamber of the pump, since the suspension mounting of these plates is tain the pressure in then subjected to a strong friction because of the force effective upon the filling piece and impairs an axial displacement. For this reason, a recess is provided in each axial plate corresponding to the shape of the area of axial load, and a sealed plunger is inserted the-rein which is provided at its side facing the pump gearing with an enlarged section in the shape of a flange.

The size of this flange is dimensioned such that it covers the entire pressure chamber between the mesh, the root line of the gears, and the tip of the filling piece which is under pressure.

The plungers can move freely in the axial direction, independently of the forces affecting the filling piece.

Since the force elfective upon the filling piece, which force must extend through the geometrical axis of the pin of the filling piece in order to avoid moments, is the central normal of the cross-sectional sealing area of the filling piece, it is necessary to pull the pressure load further upwardly on the sector area on the side of the ring gear, with respect to the sector area on the side of the pinion, toward the pin of the filling piece. For this purpose, according to the invention, arcuate stabilizing slots are provided in the flange surface of one of the axial plungers, approximately along the pitch lines of the gears, the stabilizing slot following the pitch of the ring gear being longer than the stabilizing slot following the pitch of the pinion. Thereby, the required inclined position of the sealing cross-sectional area is obtained. In order to achieve independence from the degree of precision in the manufacture of such stabilizing slots, grooves or bores are provided, extending in the direction of the sealing cross-sectional area and passing through the filling piece, which grooves or bores connect the two-sector-shaped areas sealingly resting against the gears and thereby mainthe respectively opposed tooth gaps exactly identical.

In place of the stabilizing slots in the flange of a plunger, it is also possible to provide a stabilizing slot in the extension of the balancing field at the control piston, the pressure controlled in the gaps of the teeth of the ring gear on account of this procedure being, in turn, transmitted without losses to the gaps of the pinion teeth by means of transverse grooves or bores.

Since, according to the present problem, the forces effective in the pump are to be compensated in such a manner that the loads and bending stresses produced thereby do not cause any changes in shape in the pump parts meant for sealing purposes, it has furthermore proven suitable to provide the filling piece, on the sector area on the side of the hollow wheel, with one or several slots, the ends of such slots being equally far apart from the resulting force effective upon the filling piece as the distance of the sector area on the side of the pinion from this force. Thereby, it is accomplished that the filling piece is not further compressed by forces exerting their influence upon this filling piece from the lateral direction, and thus does not assume circular arc shapes which are different from that shape corresponding to the,

crown line of the gears.

It has, furthermore, turned out to be advantageous to make the sliding surface between the ring gear and the control piston not too small, considering the high peripheral speed. For this reason, the balancing field proper in the control piston is maintained as narrow as possible, and a groove is provided on each of the two sides which is closed at its ends and connected with the balancing field via transverse slots. Thereby, the effect of the balancing field is increased to the required extent, and at the same time, an additional area portion is gained between these grooves and the balancing field proper;

' exertsonly a small 'forceupon the'ring gear.

In the following, the invention is explained in greater detail with reference to the drawing:

FIGURE 1 shows a sectionthrough an internal gear pump along the line II of FIGURE 3;

FIGURE 2 shows a section along line IIII of FIG- URE 3, but without the connecting flange;

FIGURE 3 shows a section along line III-III of FIGURE 1; V 7

FIGURE 4 is a plan view upon the working (sliding) surface of the control piston;

FIGURE 5 is a lateral View of the filling piece in the direction of arrow V of FIGURE 1;

FIGURE6 shows a section through the control piston along line VI in FIGURE 1;

FIGURE 7 is a variant of the filling piece; and

FIGURE 8 is across section through another pump of open construction.

The pump illustrated in the drawings has the drive shaftl'and the pinion 2 mounted thereon. The internal ring gear 3, meshing with the pinion, is floatingly mounted in the housing 4, and the filling piece 6 mounted on a bulged bolt 5 in such a manner thatit is rotatable and swingable. The bolt is mounted on bothsides in sliding block 7 and 7a. Each of the blocks is guided ina slot 8 of axial plates 9 and 9a. As shown in FIGURE 3, the axial plates 9'and 9a are mounted respectively on pins 10 and 11, and 10a and 11a, which, in turn, are

mounted respectively in bores in the housing 4, and in the lid 12 of the housing. In each axial plate, a recess is provided corresponding, in'the shape of its area, to that of the axial load. Plungers 14 and 14a, respectively, of the same shape and provided with packing 13 and 13a, respectively, are inserted in this recess. The plungers are, furthermore, provided with flanges 15 and 15a, re-

. spectively, for axially sealing the pressure chamber of the pump. V 1

The pressure fluid passes from the pressure chamber of thepump through a bore 16 extending through the plunger 14iand the flange 15 to the point behind the plunger,

whereby the plunger is. pressed, with its flange, against the pinion,'the-ring gear, and the filling piece. Analogvided with such a bore.

The ring gear3is pressed against the pinion Z by a control, piston 18 provided with an emptying area 17.

v The control piston is mounted on a pin 19 which, ac-

cording to FIGURE 6, passes through a slotr20 in the 24 and 24a and gasket rings 25 and 25a and act on the .two halves of the control piston 18. The pressure oil from the pressure chamber is. conducted, via radial bores 26 in the ring gears 3, to the emptying area 17 and from ously, thefother plunger 14a and its flange 15a is prothere'is passed through two channels 27 and 28 and-the two compensation pistonsto the pressure connection 29. The'compre'ssion springs have. the 'task of pressing the compensating pistons, when the pump is set into operation, against the control piston,iand=the latter against the pinion; Once the pump is in operation, the pressure fluid exerts a force 'upon the compensating pistons, there by pressing them against the control piston, which in turn presses againstthe pinion. z e

.The emptying area 17, likew se communication with thel-pressure chamber of the pump via the bores 26 in W the ring gear 3, is'dimensioned such that the bearing pres sure of the control'piston is ba'lanced'downto a minor fraction of that possible. Therefore, the control piston In the position of'the gears illustrated in the pressure chamber of the pump is sealed, at the filling piece, by the. two teeth-30 and 31, so that the, resulting 5 FIGURE 1,;

. force R at right angles to the sealing cross-sectionalarea 'Q of the'filling piece produced by the positionnfthe tooth gap 34 and,

, filling.

two teeth, extends through the geometrical axis of the filling piece pin 5. A groove 32 connects the two tooth gaps 3 3 and 34, so that an equal pressure is ambient in these gaps during the motion toward the pressure chamber.

Between the two teeth 35 and 36, there would likewise be produced a sealing cross-sectional area. However, since the resulting force thereof (central normal) does not pass through the geometrical axis of the pin 5' of the filling piece, the tip of the filling piece is provided on both sideswith an oblique cutout 37, whereby this sealing cross-sectional area is put into an inclined position, V i.e., it is now positioned between the teeth 35 and 38,

and its resultant force again passes through the geometrical axis of the pin 5 of the filling piece. Two

stabilizing slots 39 and 40 (FIGURE 2) in the flange 15, which are tapered toward their ends, serve the same purpose,

pinion,

A balancing groove 41 is, furthermore, provided'in the" flange 15. This groove carries excess pressure fluid from the meshing tooth gaps, which fluid flows to: the pressure chamber. V

In place of the stabilizing slots 39 and 40, it is also possible to provide, in the control piston 18, in, anextension of the emptying area 17,-a stabilizing groove 42 (FIGURE 4). If the corresponding bore 26 in the ring gear 3 arrives in the range 7 pressure fluid flows fromithe emptying area 17 into the via the groove 32, intothe tooth gap 33, whereby there is likewise provided in the two tooth gaps a balanced pressure buildup and a preliminary The surface portions 43 and 44 provided besides this stabilizing groove outside of the path of the bores 26of. p the ring gear are set back a small amount with respect to g area can be built the sliding'surfac'e, so that no emptyin up at this point. In addition to the emptying area17,

grooves 45 and 46 are provided which are connected with V the emptying area via slots 47 and 48. a

As shown in FIGURE 5, the filling piece :6 i s pr v de f on the suction side on both sides with a shoulder 49. so

7 that here, too, no uncontrollable pressure fields can be a v built'up. p. i a In the filling piece 6' illustrated in FIGURE 7,.{it can" .be seen that the resultant R of the hydraulic forces exerts a bending moment M upon the filling piece. In order to 5 make this bending moment'inefiective, the filling piece can i be provided withaslot 50 in'theregion of the-resultant cross section, so that the 'cross sections Q', Q at both sides of the resultant Rare of equal size. Ifdesired,it is 1 also possible to provide several slots.

According to the embodiment of It is this feature offpro viding the open housing'and' utilizing the entire oil container surrounding the pump these slots starting at the bore 16. The shorter stabilizing slot 39 extends along thepitch circle of the ofthis groove, the

FIGURE 8, the housi 7 ing 51, in a particularly advantageous embodiment for.

' the behavior of the pump whenit is set into operation and whenthe suction chamber is filled, is closed 'only in the i zone'of the axial plates 52 and the cont roIpisto'n53 and is open particularly in therzoneof the suction chambers. I f 'In the area of the mounting bore 54, a'jlink 55 is provided g connecting thelid with thebottom of thehousing. ,As'a 7' I further variation, the control piston 53is not'mounted on; a pin, but rests on a boss. 56 in the housing.1jSuch1afsolution, which inherently weakens the stability of the" ,housing considerably, is possible practically only in a pump; 55 f having the features of this invention, since by means of j. l the present invention all'bending stresses and deformations e are made ineffective by the accurate force compensation of all parts contributing to the sealing of the pressure chamber. e

as the suction chamber, which makes it possible, however, on the other hand, to operate such a pump with at least double the speed of rotation, without incurring any difficulties regarding the filling on the suction side.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

I claim:

1. A wear compensating high efliciency gear pump for pumping fluid, comprising: a sealed housing; a drive shaft mounted through the housing; a pinion gear fixedly mounted coaxially on said drive shaft; a ring gear having internal teeth of a shape and spacing permitting meshing of its teeth with the teeth of said pinion gear; said ring gear having a pitch circle substantially larger than that of said pinion gear and surrounding said pinion within said housing; a filling piece situated between said pinion gear and said ring gear; said piece shaped for sealing engagement with the tips of the teeth of the gears when the gears are in mesh; pivoting and moving means to make said piece pivotable about an axis fixed in the piece and parallel to said drive shaft and to make said axis movable; a piston means to push the ring gear into mesh with the pinion gear, thereby forming a meshing zone, and to cause the ring gear to move the filling piece into sealing engagement with the ring gear and the pinion gear; sealing means to seal laterally a pressure chamber bounded peripherally by the gears and the filling piece before the meshing zone; the piece pivoting axis movable in a direction substantially perpendicular to that of the resultant force of fluid in the pressure chamber on the filling piece; said axis located in said filling piece substantially in intersection with the direction of the resultant force of fluid in the pressure chamber on the filling piece; fluid inlet means from without the housing to the chamber bounded peripherally by the gears and the filling piece after the meshing zone; and fluid outlet means to the pressure chamber.

2. A gear pump as claimed in claim 1, said pivoting and moving means comprising: two axial plates mounted fixedly to and within said housing laterally from said gears; said plates having slots extending substantially perpendicularly to the direction of the resultant force of fluid in the pressure chamber on the filling piece; blocks slidably mounted in said slots; a bolt rotatably mounted in said blocks coaxially with the filling piece pivoting axis; said filling piece mounted fixedly on said bolt.

3. A gear pump as claimed in claim 2, said sealing means comprising: two recesses, one in each of said plates; each recess having, in a plane perpendicular to said shaft, an area greater than the area of the pressure chamber in a parallel plane; two plungers, one in each of said recesses; said plungers movable in the direction of the drive shaft and laterally sealed in said recesses; and conduits communicating between said pressure chamber and said recesses, at least one for each recess; each of said plungers having a flange shaped for sealing engagement with the lateral surfaces of-the gears and filling piece adjacent said pressure chamber.

4. A gear pump as claimed in claim 2, said filling piece having sealing cross-sectional areas and being provided with means such as grooves, slots, bores, and channels in the filling piece, to produce a force resulting from the fluid in the pressure chamber together with bearing forces effective transversely and radially upon the filling piece, to obtain a total load which extends through the geometrical axis of said bolt of said filling piece.

5. A gear pump as claimed in claim 4, said filling piece being provided with at least one cavity extending in the direction of said sealing cross section areas with at least one cavity connecting two sealing surfaces of the filling piece with each other; said surfaces sealingly engaging said gears; the tip of said filling piece being provided with deflecting means such as cutouts to deflect said pressurized fluid to different positions along said filling piece, said deflecting means extending obliquely along at least one side of the said tip.

6. A gear pump as claimed in claim 4, said filling piece provided on the sector area on the side of the ring gear, with at least one slot whose inner end is spaced a distance from the resultant force eflective upon the filling piece equal to the distance of the sector area on the pinion side from this line of force.

7. A gear pump as claimed in claim 4, said filling piece provided with shoulders in the suction region, said shoulders being provided on both parallel surfaces of said piece perpendicular to said drive shaft.

8. A gear pump as claimed in claim 1, said piston means including a control piston, having an emptying area, said control piston provided with grooves closed at their ends and extending in parallel to the control piston, said grooves being connected with the emptying area by transverse slots.

9. A gear pump as claimed in claim 8, said control piston having a stabilizing groove extending peripherally from the emptying area and area portions (43, 44) positioned beside this groove, said area portions being recessed and in communication with the inner space of the housmg.

10. A gear pump as claimed in claim 3, characterized in that stabilizing slots are provided in the flange of at least one of the axial plungers, said slots extending approximately along the pitch circles of the gears, these slots emanating from a conduit communicating between the pressure chamber and the recess, the slot (40) located in the region of the pitch circle of the ring gear being longer than the slot located in the region of the pitch circle of the pinion.

11. A gear pump as claimed in claim 3, said flange of one of the axial plungers provided with a compensating groove in the meshing zone, said compensating groove extending in the direction of the depression (recess) (16) of the stabilizing slots (39, 40).

12. A gear pump as claimed in claim 8, said control piston further including guiding means attached to the housing.

13. A gear pump as claimed in claim 2, the pump housing being cut away outside the region of the axial plates and the piston means, and further including an oil container surrounding the pump and serving as a suction chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,604,802 10/ 1926 Brenzinger 103-126 1,646,615 10/ 1927 Furness 103-126 2,482,713 9/1949 Jones 103-126 2,544,144 3/1951 Ellis 103-126 2,875,700 3/1959 Hardy 103-126 2,915,982 12/1959 Crandall 103-126 3,136,261 6/1964 Eckerle et al 103-126 3,265,005 8/1966 Ringgenberg 103-126 3,270,679 9/1966 Sand et al 103-126 FOREIGN PATENTS 551,485 6/ 1932 Germany.

DONLEY J. STOCKING, Primary Examiner. W. J. GOODLIN, Assistant Examiner. 

1. A WEAR COMPENSATING HIGH EFFICIENCY GEAR PUMP FOR PUMPING FLUID, COMPRISING: A SEALED HOUSING; A DRIVE SHAFT MOUNTED THROUGH THE HOUSING; A PINION GEAR FIXEDLY MOUNTED COAXIALLY ON SAID DRIVE SHAFT; A RING GEAR HAVING INTERNAL TEETH OF A SHAPE AND SPACING PERMITTING MESHING OF ITS TEETH WITH THE TEETH OF SAID PINION GEAR; SAID RING GEAR HAVING A PITCH CIRCLE SUBSTANTIALLY LARGER THAN THAT OF SAID PINION GEAR AND SURROUNDING SAID PINION WITHIN SAID HOUSING; A FILLING PIECE SITUATED BETWEEN SAID PINION GEAR AND SAID RING GEAR; SAID PIECE SHAPED FOR SEALING ENGAGEMENT WITH THE TIPS OF THE TEETH OF THE GEARS WHEN THE GEARS ARE IN MESH; PIVOTING AND MOVING MEANS TO MAKE SAID PIECE PIVOTABLE ABOUT AN AXIS FIXED IN THE PIECE AND PARALLEL TO SAID DRIVE SHAFT AND TO MAKE SAID AXIS MOVABLE; A PISTON MEANS TO PUSH THE RING GEAR INTO MESH WITH THE PINION 